DE1644761B2 - Process for the production of impact-resistant, elastic and hard coatings - Google Patents

Description

HO-

-CH ₈

in which / ι stands for 5 to 20, in per se known Way cures with aminoplasts or their defined precursors

i5

The invention relates to a process for the production of optionally pigmented coatings by curing a mixture consisting of 60 to 90 parts of hydroxyl-containing linear Polyester on the one hand and 40 to 10 parts of aminoplasts on the other hand in the presence of conventional paint solvents and optionally in the presence of acids as catalysts.

It is already known from column 5 of the German Auslegeschrift 1 015 165, by curing a mixture from a phthalic acid-fumaric acid-propylene glycol polyester on the one hand and a butylated melamine-formaldehyde resin on the other hand to produce coatings. The resulting paint films, however, had only poor chemical resistance. About that In addition, our own experiments showed that mixtures of linear polyesters on the one hand and a mel-amine-formaldehyde resin on the other hand was cured and 40 to 10 parts of aminoplasts on the other hand in the presence of customary LaeWösmittel and optionally in the presence of acids as catalysts, characterized in that a bydraxylgruppenbaltiges polycarbonate of the general formula

H ^X -CH.-OH

the fact that the coatings obtained are stretchable, but are soft (see comparative examples 1 and 2).

From Auslegeschrift 1 015 165 is also known that one chemically extremely resistant Coatings are obtained when an alkylated melaroin-formaldehyde or urea-formaldehyde condensation product is used combined with a linear polyester made by polyesterification of a dicarboxylic acid with a diol of the general formula

H (OR)

O-

- A - '

■;, - O (RO)., H

was obtained in which A is a 2 ^ alkylidic radical with 3 to 4 carbon atoms, R stands for an alkylene radical with 2 to 3 carbon atoms, m and η are each at least 1 and the sum of »7 and /; is not «larger than 3. The coatings obtained in this way are hard, but very brittle (see Comparative Examples 3 and 4).
The invention is based on the object of

to produce trains in which high elasticity and impact resistance are paired with great hardness.

According to the invention, this object is achieved by using a hydroxyl-containing polycarbonate the general formula

HO-

-CH ₁ - / H

CH ₂ -OCO

CH ₂

H, - CH ₂ -OH

in which η stands for 5 to 20, cures in a manner known per se with aminoplasts or their defined precursors.

Dihydroxy compounds containing carbonate groups of the above general formula can be obtained in a simple manner by a process which is not yet part of the prior art by reacting 1,4-bis (hydroxymethyl) cyclohexane with phosgene. Here, 1,4-bis (hydroxymethyl) cyclohexane can be used in its trans or cis form or as a mixture of both forms. This method allows a certain desired value of n to be set, where η represents the average value of a series of polymer homologues.

The known reaction products of aldehydes, in particular, come as suitable aminoplasts Formaldehyde, with several amino or amido-bearing substances in question, z. B. with melamine, Urea, Ν, Ν'-ethylene urea, dicyandiamide and benzoguanamine. The aminoplasts modified with alcohols are particularly suitable. Instead of these resinous precondensates can also have their defined, optionally etherified precursors, e.g. B.

Hexamethylolmelamine, can be used. A large number of commercially available aminoplasts can be combined with the linear polyesters used according to the invention are available.

To produce the coatings, polycarbonate and aminoplast are first mixed in the usual paint solvents, z. B. xylene or butanol, dissolved; the weight ratio of polycarbonate to aminoplast vary between 60:40 and 90:10. The re-

sultierende resist is then optionally pigmented, coated, and baked at temperatures of 100 to 200 ⁰ C. The crosslinking reactions that take place are catalytically accelerated by acids. For this reason, it is advisable to add acidic substances to the paint. When the addition of for example 2%-toluenesulfonic p (based on the aminoplasts) extends, the cross-linking at 130 ⁰ C sufficiently fast. Mixtures that dry at room temperature can also be produced by adding larger amounts of acid.

The coatings produced according to the invention have an abundance of good properties. They are high gloss and resistant to solvents such as

I 644 761 3 4

Xylene, gasoline-benzene mixtures, esters and ketones. einge- applied and for 30 minutes at 13O ⁰ C Burns during salt spray tests, tropical tests and tests. The resulting films have a hardness

in the Weatherometer they showed an excellent performance of 203 seconds, a deep drawability before 8.3 mm

Weather resistance. and an impact depression of 5 mm. The most outstanding property of the invention.

however, custom-made coatings is the pairing of Example 3

high ductility and impact resistance with high 267g in a 30% solution of a polycarbonate of

Hardness. above general formula («= 13) in xylene

The elongation behavior of coatings is described using 40 g of a 50% strength solution of hexa- (methoxywöhnlicb by mixing the Erichsenw methoxy-melamine in xylene. The test is carried out using a deep test (according to DIN 53 156) and as a measure the paint sample sheets aufgestriehen and 30 Minufür the extensibility the cupping of painted sheet metal th at 190 ⁰ C baked. the resulting in mm indicates where the mineral layer to tear loading films have a hardness of 209 seconds, a Tiefginnt. essential for this method of testing is that drawability of 10 microns and an impact indentation of the deformation of the coating is carried out slowly (first 15 "> rom 5 to shear. 0.2 mm / sec) a clue for encrypting _R.... . coatings hold at sudden comparison B e s 1 e ρ 1 l 4 modeling was examined by a so-called impact the paint of example 3, 0.4 g p-toluene to obtain tiefungsmessung This measurement may sulfonic acid were added;. then he will iu * Pc Upper metal sheets, for example, with the impact deepening device 226 / D, which is applied for 20 minutes and burned out for 30 minutes at 130 ° C. from Erichsen, Hemer-Sundwig. The resulting films have a hardness. In this device, a hemisphere with a radius of 200 seconds, a deep-drawability of 10 mm radius of 10 mm is made by a falling weight into the and an impact indentation of> 5 mm.
Pressed in sheet metal (unpainted side up). By . .
Change of the height of fall can be the depression 15 B e 1 s ρ 1 e 1 3
vary. The indentation value is given (in mm), 234 g of a 30% solution of a polycarbonate at which the lacquer layer begins to tear. (The values given in the above general formula («= 10; examples are given in xylene were obtained in this way with 54.5 g of a commercially available 55% solution of one. In many examples, the value with> 5 mm of melamine-formaldehyde Condensate in a xylene is indicated because the device described is mixed with the 30 butanol mixture (1: 1). For testing, 1 mm thick deep-drawn steel sheets are used to test the paint on test panels and facial expressions do not allow a greater effect /.) th baked for a long time at 190 ^° C. The resulting

As with the description of the prior art films have a hardness of 154 seconds, a deep

has already been carried out and a comparative forgeability of 8.2 mm and an impact indentation of

search is occupied, there are already coatings of linear 35> 5 mm.

Polyesters and aminoplasts are known to be stretchy. . . ,

are (and then also an impact stress from- ^it P ' ^e

keep); However, these coatings have very little. The paint from Example 5 is 0.45 g of p-toluene

Hardening (according to DIN 53 157). On the other hand, sulfonic acids are added; then it is put on test panels

Coatings of high hardness known, but applied in a non-stretchable manner and applied for 30 minutes at 130 ° C.

and do not withstand impact stress. The resulting films have a hardness of

keep. In contrast, the 212 seconds according to the invention, a deep-drawing ability of 8.1 mm and

Hold coatings have both high impact resistance and an impact depression of > 5 mm.

Extensibility as well as a great hardness. _R 17

This property profile gives the coatings a 45 Example /
versatile application. In addition to the painting of By pigmenting the individual parts described in Example 5, which are exposed to a high impact paint with 50 g of titanium dioxide a paint color, the painting of made, applied to test panels and 30 minutes of materials into consideration, the later - z . B. baked through long at 190 ° C. The resulting films are stamping - deformed. 50 have a hardness of 201 seconds, a deep- ^{drawability of 9.1 mm and an impact indentation of Beis} P 'e11> 5 mm.

234 g of a 30% strength solution of a polycarbonate from Example 8
above general formula (n = 13) in xylene

with 54.5 g of a commercially available 55 "solution of a MeI 55 234 g of a 30% solution of a polycarbonate amine-formaldehyde condensate in a xylene-buta of the above general formula (/) = 10) in a xylene wernol mixture ( . 1: 1) is mixed to test the 50 g of a commercial 60% strength solution of a lacquer aufgestriehen on test plates and 30 minutes urea Formaidehyd condensate in butanol and baked at 19O ⁰ C for the resulting films with 0.45. g p-toluenesulfonic acid are mixed. wise to test a hardness (according to DIN 53 157) of 176 seconds 60, the paint is aufgestriehen to test plates, and (according to DIN 53 156) baked to a deep-drawability of 30 minutes at 130 ⁰ C. the The resulting films have a hardness of 209 seconds, the thickness of the films on which the measurements were taken, a deep-drawability of 9.7 mm and an impact was 50 in all examples up to 60 μ. deepening of> 5 mm.

Example 2 ^{3 Example9} The paint from Example 1 is 0.45 g of p-toluene-234 g of a 30% solution of a polycarbonate

sulfonic acid added; then he will be on test panels above general formula (n = 8) with 27.3 g

a commercial 55% solution of a melamine Foi rn with 25 parts of TiQ ₁ pigmented. The

aldehyde condensate in a xylene-butanol-Ge lacquer applied to test panels and 30 minutes

mixture (1: 1) and 24.2 g of a commercial 62% aqueous solu- baked at 190 ⁹ C. The resulting films

solution of a benzoguanamine-formaldehyde condensate have a hardness of 23 seconds, a deep-drawing

mixed in butanol. The paint is tested for a capacity of 7.7 mra and an impact depression of

Test sheets on painted and on for 30 minutes at> 5 ram,

Baked in at 190 ° C. The resulting films have Comparative Example 2

a hardness of 156 seconds, a deep drawing ability

of 10 mm and an impact depression of> 5mm. The paint from comparative example 1 will be

. . ίο 0.225 g of p-TomoJsulfonic acid added; then the

Example 10 Paint applied to test panels and 30 minutes 0.45 g of p-toluene are baked at 130.degree. C. for a long time on the paint from Example 9. The resulting films

sulfonic acid added; then it will have a hardness of 25 seconds on test sheets, a deep-drawing

applied for 30 minutes at 13O ⁰ C skill einge- of 7.9 mm and an impact indentation of

burns. The resulting films have a hardness of 15> 5 mm.

of 215 seconds, a deep-drawing ability of 8.2 mm ..,. ,,. . ,,

UBd an impact depression of> 5 mm. Comparative example 3

-, n 1580 parts (5 moles) of the symmetrical bis (hydroxy-

Example 11 Ethyl) ethers of bisphenol-A are 400 parts

The paint from Example 9 is mixed with 300 g of titanium dioxide 20 (4 mol) of succinic anhydride while passing it through

pigmented, applied to test panels and 30 mi of a nitrogenous current for 6 hours at 180 ^z C

Baked in for a long time at 190 ° C. The resulting heats. The remaining quantities of reactive water are then

Films have a hardness of 102 seconds, a depth of about 20 Torr by applying a vacuum

drawability of 10 mm and an impact indentation from a distance. The polyester produced in this way has an acid number

2.2 mm. Despite the high pigment content, this remains 25 out of 5; he is in a xylene methyl ethyl ketone

retain full extensibility; also the impact deepening cyclohexanone mixture (1: 1: 1) to a 50% strength

eats quite well. Solution solved. 70 parts of this solution are with

... . ,,. ... 30 parts of a commercially available, 50% content

Comparative Example 1 dilute solution of a melamine-formaldehyde

316 parts of adipic acid (2.16 mol), 480 parts of phthalic condensate in a xylene-butanol mixture (1: 1), acid anhydride (3.24 mol) and 374 parts of ethylene glycol are mixed. This varnish is pigmented with 25 g of TiO ₂ (6.5 mol) of advantage under a stream of nitrogen, applied to test plates, and 30 minutes current slowly to 160 to 200 ⁰ C heated until 118Teile baked at 190 ⁰ C. The resulting films have gone over distillate. A hardness of 190 seconds, a deep drawing, that the transition temperature at the top of the 35 capability of 1.9 mm and an impact depression of the column does not exceed ^{100 ° C. is to be pointed out.} Then <1 mm.

with increasing vacuum 19 parts in 6 hours. . ...

distilled off. The polyester has an acid number of 3, Comparative Example 4

up to 4 and a hydroxyl number of 56; it will be in one of the paint colors from comparison example 3

Xylene - methyl ethyl ketone - cyclohexanone mixture 40 0.225 g of p-toluenesulfonic acid was added; then the

(1: 1: 1) dissolved to a 50% solution. 70 parts of paint applied to test panels and 30 minutes

of this solution are mixed with 30 parts -dner, long commercial baked at 130 ⁰ C. The resulting films

a solution diluted to a content of 50% have a hardness of 126 seconds, a deep-drawing

Melamine-formaldehyde condensate with a xylene capacity of 1.1 mm and an impact depression of

Butanol mixture (1: 1) mixed. The clear coat turns 45 <1 mm.

Claims (1)

i 644 Claim: Process for the production of optionally pigmented coatings by curing a mixture consisting of 60 to 90 parts bydroxylgruppenhaltiger linear polyester on the one hand